This invention relates to safety barriers for roadways, of which many variations have been proposed and some of which are in use. Thus, the prior art varies from spaced posts of wood, metal and cement, longitudinal members thereof, continuous concrete walls of minimized curb height to more than vehicle height, and metal fences etc., all of which have for their primary function the prevention of vehicles leaving the roadway. There are different modes of operation attributed to such barriers, those which partially or completely collapse upon vehicle impact, and those which remain intact and in place as is the case with the present invention. Also, there are barriers which capture the vehicle wheels so that the vehicle is guided straight ahead, and those which return the vehicle to the roadway, it being a general object of this invention to provide a wheel straightening effect, to prevent or reduce impact forces, and to provide a restriction that prevents or reduces violent rebound of the vehicle onto the roadway.
The height of vehicle safety barriers is a serious problem, in that severe body damage can be caused thereby. That is, the side of a vehicle coming into forceful contact with a barrier wall can virtually destroy the side of said vehicle. On the contrary, it is an object of this invention to prevent or reduce vehicle body damage, by restricting the height of the barrier wall without losing its effectiveness. In practice, a full depth of the tire cross section is engageable with the barrier wall, while the vehicle body parts and namely the front bumper normally clear said barrier wall.
The wheel diameter and chassis height of passenger vehicles vary to some degree, the wheel axis normally being ten to twelve inches above the pavement, and the underside front bumper level normally being twelve to fifteen inches above the pavement. It is an object of this invention to confine barrier wall engagement with the tire as much as practically possible, by restricting the barrier wall height to about twelve inches or to approximately the radius of the vehicle wheel or tire, and so that the front bumper tends to clear the barrier wall under adverse circumstances. This clearance of the front bumper, or that portion of the vehicle chassis, is increased as next described.
The safety barrier of the present invention is of the type which includes an inclined shoulder plane rising to the barrier wall, in which case the body of a vehicle approaching at high velocity will depress, dependent upon softness of its suspension, relative to said shoulder plane, thereby causing the body and/or front bumper to strike the barrier wall. However, it is an object of this invention to preclude or reduce this tendency by providing offset shoulder planes and one of which elevates the oncoming vehicle wheel relative to the other plane from which the barrier wall projects. Overturning or displacement of wall barriers has been a problem, and all of which is solved herein by the extensive shoulder plane or planes completely underlying the active portions of the angularly turned vehicle wheel, and by the comparatively low lying and unobtrusive barrier wall. It is to be understood that the functions are dynamic and occur only when the vehicle encounters this safety barrier at substantial velocity. This does not however preclude effective low velocity encounters.
Return under control to the roadway; of a vehicle that is temporarily or partially out of control is to be desired. There are safety barriers proposed for this specific purpose, but with no restriction to or damping of the rebound effect. That is, the prior art is devoid of steering correction combined with rebound damping, it being an object of this invention to provide steering correction combined with rebound damping, whereby the course of the vehicle is corrected and so that it returns to the roadway with reduced violence.
The travel angle of vehicle approach to safety barriers of the type under consideration can vary, for example up to 25.degree. with respect to the longitudinal disposition of the barrier wall, any angle in excess of 25.degree. being considered to be more or less beyond that which can be expected and beyond control. However, most angular approaches which are of concern occur within the range of 12.degree. to 15.degree., and accordingly the safety barrier as it is herein disclosed is designed to the severe angle of 25.degree., more than adequate to accept the 12.degree. to 15.degree. approach. As will be described, this approach angle is significant, as the rebound barrier is positioned to effectively engage the returning wheel, whereby the return of the vehicle to the roadway is restricted by a damper function.